Manufacture of ferrotungsten



.155 Church Road, Battersea, London,

Patented Nov. 28, 1922.

UNITED STATES JOHN MUBDOCH SKELLEY AND JAMES MERSON, OF BATTERSEA,LONDON, ENGLAND,

PATENT OFFICE.

ASSIGNOBS TO CONTINUOUS REACTION COMPANY, LIMITED, OF LONDON, ENGLAND.

MANUFACTURE OF FERROTUNGSTEN.

Io Drawing.

To all whom it ma concem:

Be it known that we, JoHN MURDOOH,

SKELLEY and JAMES MnRsoN, both subjects of the King of Great Britain,residin at n land, have invented new and useful Iniprovements in theManufacture of Ferrotungsten, of which the following is a specification.

-This invention relates to improvements in the manufacture offerrotungsten, i. e. alloys of tungsten and iron in various proportions,containing up to about ;85 per cent of tungsten respective These alloyshave itherto been manufactured as a rule .from ores or mixturescontaining iron an tungsten by reduction either in the electric furnaceor by the alumino-thermic process. In some cases the alumino-thermicreduction has been effected by means of a mixture of aluminium andferrosilicon, but it has not been possible to dispense with the use'of asubstantial proportion of aluminium, which is a relatively costlyreducing agent.

The present invention is based upon the discovery that if ores ormixtures containing iron and tungsten in the form of oxides be mixedwith pulverized silicon or ferrosilicon and a suitable oxidizing agentcontaining nitrogen such as sodium nitrate, but without aluminium,reaction may be initiated at a point in a cold or heated mixture as inthe alumino-thermic process, and if suitable proportions of theingredients be used the reaction proceeds to completion,

ferrotungsten practically free from carbon and silicon resultinAccording to th1s invention, therefore, ferrotungsten is producedwithout the aid 'of aluminium by the silico-thermic reduction of amixture of oxide ofiron with oxide of tungsten, or of an ore containingiron nitrate.

As a rule, the richer the reducing agent is in silicon, the better isthe reaction. Commercial silicon, which contains up to about 95% Si, orferrosilicon containingfrom 90 to 70% Si, can be used with excellentresults. It will be understood that with ferro- Application filed. Kay29,

silicon containing lower proportions of silicon the reaction becomesmore sluggish and The following example illustrates the.

invention A commercial tungsten ore is subjected to a preliminarypurification to remove any tin and other undesired constituents presentand is then roasted till free from sulphur.

Of the product, containing per cent of- WO,, 16 per cent of FeO and 8per cent of Mn(), 100 lbs; are mixed with 20% lbs. of ferrosilicon (90%Si) and 5 lbs. of sodium nitrate. Preferably 5 lbs. of calcium fluorideare added to enhance the fluidity of the slag. The mixture is put into acrucible and reaction is initiated as in the aluminothermic process. 1

What we claim is 1. The manufacture: of ferrot ungsten without the aidof aliminium by the sllicothermic reduction of iron oxide and tungstenoxide in the presence of an oxidizing agent containing nitrogen.

2. The manufacture of ferrotungsten without the aid of aluminium by' thesilico-- thermic reduction of iron oxide andtungsten oxide in thepresence of sodium nitrate.

3. The manufacture of ferrotungsten by purifying tungsten ore to removeany tin and other undesired constituents present, roasting the residueto remove sulphur, mixing with the product ferrosilicon and an oxidizingagent containing nitrogen, and producing reaction as in the we knownalumino-thermic process.

- 4. The manufacture of ferrotungsten without the aid of aluminum by thesllicothermic reduction of iron oxide and tungsten oxide in the presenceof a nitrate oxidizing agent.

' 5. The manufacture of ferrotungsten by purifying tungsten ore toremove any tin and other undesired constituents pres ent, roasting theresidue to remove sulphur, mixing with the product ferrosilicon and anitrate oxidizing agent, and producing reaction as in the Well knownalumino-thermic oxide, 8 parts of manganese oxide, 20% parts offerrosilicon and 5 parts of sodium nitrate. 10

In testimony that We claim the foregoing as our invention We have signedour names this 17th day of May, 1922.

JOHN MURDOCH SKELLEY. JAMES MERSON.

